Placebook [geographics.cz] aims to provide a visual overview on how Facebook users are distributed around the world. As a unique feature, any Facebook users can log into the system, in order to receive a map and all relational statistics about their own personal friend network.

The map has been designed in the typical Facebook blue style, and includes a small data graphics dashboard showing the absolute counts of users per country, the proportion of users within a population, and the distribution per age group. Not surprisingly, this project was the 2010 winner of the NACIS Student Web Mapping Competition.

It's not the proportion of users in different age groups, but the distribution of users by age groups. What a mistake ! And this map is the winner of a student competition ! I hope it's not a geography students competition...